If I have to many choices I don't use them. My goal is to have under 6 that are in rotation, if I get one in the same color family, I will let the other one go. (I'm pretty fickle though, if I have two different styles in the same color family it won't count ) I would say if you don't use it every couple of months, it's time to let it go.
I agree with Ladybug. I too am trying to trim down my handbag collection to only Balenciaga, Hermes, Chanel, and a couple exotic skin ones. It is true that when I have SO many handbags, I don't use most of them, and it's simply a big waste.
I understand how some member feel short-changed when you buy a bag for $1000 only to turn around and sell it for $700 in a couple months. So I recommend going to reputable resellers who have reasonable consignment contracts. Usually with these resellers, since their reputation is great and they have a decent collection, they usually can list items for retail or slightly above retail.
Right now, I have over 100 handbags. My goal to trim down will definitely be a long term one.